Controlled flow administration set

ABSTRACT

A flow control device includes a connector defining a first receiving formation for receiving a first conduit, a second receiving formation for receiving a second conduit and a cross member separating the first receiving formation and the second receiving formation. An orifice plate is received in the cross member to control flow of fluid, in use, through the conduits received in the first and the second receiving formations of the connector, the orifice plate defining at least one substantially frustoconical orifice.

The present application claims the priority benefit of and incorporatesherein by reference, in their entireties, the disclosures of U.S. patentapplication Ser. No. 12/083,042, filed Apr. 3, 2009, InternationalApplication No.: PCT/AU2006/001465, filed Oct. 5, 2006, which designatedthe United States of America, and Australian Provisional PatentApplication No. 2005905494 filed on Oct. 5, 2005.

FIELD OF THE INVENTION

This invention relates to a flow control device. More particularly, theinvention relates to a flow control device particularly, but notnecessarily exclusively, for use in an intravenous (IV) administrationset, to an orifice plate for a flow control device and to a componentfor an IV administration set.

BACKGROUND OF THE INVENTION

At present, infusion of fluids into a patient is managed by medicalpersonnel. Fluids are infused parenterally into a patient for a varietyof reasons. It is often critical that the fluid being administered isinfused into the patient's body in the required doses and flow rates.

This is usually done either manually using a roller clamp orautomatically using an infusion pump. Manual roller clamps areinaccurate and are difficult to set to maintain an accurate flow rate.In addition, when applied to a length of plastics conduit, the plasticsconduit itself may, in due course, plastically deform resulting in aloss of clamping action of the roller clamp. This could have thepotentially serious consequences of an unregulated supply of fluid intothe patient's body.

Infusion pumps, while maintaining an accurate flow rate, are expensiveitems. In addition, because an infusion pump is an electromechanicaldevice, there is a risk of failure of the infusion pump which, onceagain, has potentially extremely serious consequences. Further, with theincreasing age of the population there is more pressure for bed placesin hospitals resulting in an increasing homecare market. Providinghomecare patients with infusion pumps is expensive and has attendantrisks as well. In addition, in large parts of the world, there areinsufficient funds to make infusion pumps available to patients, whetherin hospitals or in homecare.

Also, in the case of roller clamps, there is a continuous need forvigilance by medical personnel to ensure that the fluid is being infusedat the desired flow rate. Often, in parts of the world, medicalpersonnel are in short supply and are unable to provide the requisiteduty of care.

A need therefore exists for a device which requires minimal humanintervention, is not able to be tampered with, whether by the patient orby medical personnel, and which requires very little, if any, trainingor supervision to use.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a flowcontrol device which includes

a connector defining a first receiving formation for receiving a firstconduit, a second receiving formation for receiving a second conduit anda cross member separating the first receiving formation and the secondreceiving formation; and

an orifice plate received in the cross member to control flow of fluid,in use, through the conduits received in the first and the secondreceiving formations of the connector, the orifice plate defining atleast one substantially frustoconical orifice.

It will be appreciated that, with this configuration of connector, thereis a chamberless communication between the ends of the conduit and theorifice plate. Thus there is no chamber in which air bubbles can formwhich could inhibit proper operation of the flow control device.

Further, while a single orifice in the device should normally providesufficiently accurate metering of flow rate, it may be necessary, wheregreater accuracy is required, to use a plurality of smaller orifices inparallel. In general, each orifice has an accuracy of +/−3%. It will beappreciated that, if a plurality of orifices are used together, theworst case scenario would be an inaccuracy in the flow rate of +3% or−3%. The likelihood, however, is that there would be an averaging out ofinaccuracies over the orifices resulting in an overall greater accuracyof flow rate over all the orifices. Hence, there may be circumstanceswhere the orifice plate comprises a plurality of orifices.

The connector may comprise a cylindrical housing defining a pair ofopposed sockets, the sockets forming the receiving formations with atransversely extending web defining the cross member. At least the webmay be of a resiliently flexible material. Preferably, the housing is aone-piece unit of a resiliently flexible material such as a polymeric orelastomeric material which facilitates lateral deformation of thehousing for priming purposes, i.e to prime a system, such as an IV set,with which the flow control device is used.

The orifice plate may be of a rigid material, such as a metal or asuitably rigid plastics material. Preferably, the orifice is formed inthe plate by laser drilling. Laser drilling enables an orifice ofsufficiently accurate dimensions to be formed. It will, however, beappreciated that the orifice plate could be of a flexible material, suchas a polymeric material. Further, although laser drilling is thepreferred form of forming the orifice, the orifice could be formed inother ways such as, for example, by mechanical drilling, chemicalforming, using ultraviolet radiation, or the like.

For any given angle of frustum of the orifice, flow rate through theorifice may be directly proportional to a cross-sectional area of asmaller opening of the orifice. Flow rate through the orifice may begoverned by a linear relationship of the form:y=mx±cwhere:

y is flow rate in ml/hr;

x is cross-sectional area of the smaller end of orifice in microns²; and

m and c are constants governed by the angle of the frustum.

The angle of frustum of the orifice may be in the range of about 15° to50°, more particularly, in the range of about 20° to 28° and, optimally,about 24°.

The orifice may have a diameter (as measured at its smaller opening) inthe range from about 1 to about 700 microns, more particularly about 30to about 700 microns. Further, the orifice may have an aspect ratio,being defined as the ratio between a length of the orifice and itsdiameter, which is less than or equal to 10 and, preferably, about 2.

The connector may be of a coloured material. More particularly, theconnector may be colour coded with each colour being associated with aparticular flow rate.

According to a second aspect of the invention, there is provided a flowcontrol device which includes

a connector defining a first receiving formation for receiving a firstconduit, a second receiving formation for receiving a second conduit anda cross member separating the first receiving formation and the secondreceiving formation, the connector being a one-piece unit of aresiliently flexible material which facilitates lateral deformation ofthe connector for priming purposes; and

an orifice plate, defining at least one orifice, received in the crossmember to control flow of fluid, in use, through the conduits receivedin the first and the second receiving formations of the connector.

Once again, the orifice plate may be a rigid member received in thecross member, lateral deformation of the connector causing the formationof priming ports between the orifice plate and the cross member.

The connector may comprise a cylindrical housing defining a pair ofopposed sockets, the sockets forming the receiving formations with atransversely extending web defining the cross member.

The orifice plate may be of a rigid material. Preferably, the orifice isformed in the plate by laser drilling.

The orifice may be a frustoconical orifice and, for any given angle offrustum of the orifice, flow rate through the orifice is directlyproportional to a cross-sectional area of a smaller opening of theorifice.

The connector may be of a coloured material. More particularly, theconnector may be colour coded with each colour being associated with aparticular flow rate.

According to a third aspect of the invention, there is provided anadjustable flow rate flow control device which includes

a fluid delivery arrangement having an inlet and defining a plurality ofspaced orifices in communication with the inlet; and

a passage defining member displaceably arranged relative to the deliveryarrangement, the passage defining member defining a passage which isable to be brought into flow communication with a desired number oforifices to achieve a desired flow rate through the outlet by adjustingthe position of the passage defining member relative to the deliveryarrangement; and

an outlet in communication with the passage of the passage definingmember.

The device may include a supply duct in flow communication with thepassage defining member.

The fluid delivery arrangement may include a housing defining a firstflow path, the passage of the passage defining member defining a secondflow path. Further, the fluid delivery arrangement may include aseparating element separating the first flow path from the second flowpath, the separating element having the orifices.

The separating element may be a gasket of a resiliently flexiblematerial, the gasket defining the orifices. The orifices may be definedin the gasket by a plurality of rigid orifice plates, each orifice platedefining at least one orifice.

In one embodiment, the passage defining member may include a rotaryactuator which is rotatably arranged relative to the housing, thepassage being defined in a body of the rotary actuator. The outlet maybe defined in the housing and the gasket may have an opening definedthrough it in alignment with the outlet so that fluid that has passedthrough the orifices is able to flow out through the outlet via thepassage of the passage defining member.

In another embodiment, the supply duct may constitute the passagedefining member, the supply duct being slidably arranged relative to thedelivery arrangement to bring the desired number of orifices into fluidcommunication with the passage.

Each orifice may be formed by laser drilling. Laser drilling enables anorifice of sufficiently accurate dimensions to be formed.

Each orifice may be a frustoconical orifice having the features andcharacteristics described above with reference to the first aspect ofthe invention.

According to a fourth aspect of the invention, there is provided acomponent for an intravenous (IV) set, the component including a conduitof a silicone material.

The silicone material may be reinforced to inhibit kinking and toenhance the elasticity of the conduit. The reinforcing may be ahelically wound reinforcing member carried in a wall of the conduit. Thereinforcing member may be selected from the group consisting of aplastics material, such as nylon, a metal material, such as stainlesssteel, and a shape memory alloy.

The component may include a flow control device for interconnecting twolengths of conduit, the flow control device being as described abovewith reference to either the first aspect of the invention or the secondaspect of the invention, the connector of the flow control device beingof a silicone material. Instead, the component may include a flowcontrol device for interconnecting two lengths of conduit, the flowcontrol device being as described above with reference to the thirdaspect of the invention, at least one of the passage defining member andthe supply duct being of a silicone material.

According to a fifth aspect of the invention, there is provided acomponent for an intravenous (IV) set, the component including a conduitof a reinforced polymeric material.

The reinforcing may be a helically wound reinforcing member carried in awall of the conduit. The reinforcing member may be selected from thegroup consisting of a plastics material, such as nylon, a metalmaterial, such as stainless steel, and a shape memory alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional side view of a flow control device inaccordance with an embodiment of a first aspect of the invention;

FIG. 2 shows a sectional side view of the flow control device of FIG. 1,in use;

FIG. 3 shows a schematic, sectional side view of an adjustable flow rateflow control device in accordance with a first embodiment of a secondaspect of the invention;

FIG. 4 shows a schematic, sectional side view of an adjustable flow rateflow control device in accordance with a second embodiment of the secondaspect of the invention;

FIG. 5 shows a front view of a further embodiment of an adjustable flowrate flow control device;

FIG. 6 shows a side view of the device of FIG. 5;

FIG. 7 shows a plan view of the device of FIG. 5;

FIG. 8 shows a three dimensional, exploded view from the rear of thedevice of FIG. 5;

FIG. 9 shows a schematic sectional side view of another embodiment of anadjustable flow rate flow control device;

FIG. 10 shows a sectional side view of an embodiment of an orificeplate, in accordance with another aspect of the invention, for use withthe devices of FIGS. 1-9;

FIG. 11 shows a graph of flow rate vs. cross-sectional area for theorifice plate of FIG. 10; and

FIG. 12 shows two variations of a component for an IV set in accordancewith further aspects of the invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring initially to FIGS. 1 and 2 of the drawings, an embodiment of aflow control device is designated generally by the reference numeral 10.The flow control device 10 comprises a connector in the form of ahousing 12. The housing 12 defines a first receiving formation 14 inwhich a first conduit 16 (FIG. 2) is received and a second receivingformation 18, spaced from the first receiving formation 14, in which asecond conduit 20 is received. The receiving formations 14 and 18 arearranged on opposed sides of a cross member, or web, 22. The web 22supports an orifice plate 24, the orifice plate 24 being a separatecomponent and defining a frustoconical orifice 34 which will bedescribed in greater detail below.

The housing 12 is of a resiliently flexible material. The housing 12 isof a polymeric material or, instead, is of an elastomeric material, moreparticularly, a silicone material.

It will be noted that each receiving formation 14, 18 is slightlytapered to facilitate a snug fit of the conduits 16, 20 in the receivingformations 14, 18 respectively and to impose a clamping-like action onthe conduits 16 and 20 to retain them in their respective receivingformations 14, 18. It will also be noted that an end of each conduit 16,20 butts up against the web 22 so that there is chamberlesscommunication between the conduits 16, 20 and the orifice 34.

To facilitate insertion of the conduits 16, 20 into their associatedreceiving formations 14, 18, an access opening of each receivingformation 14, 18 has a chamfered edge 26.

As described above, the housing 12 is of a resiliently flexiblematerial. It will be appreciated that the orifice plate 24 has verysmall dimensions measured on the micron scale. It is necessary to primea system with which the flow control device 10 is used to effect fluidflow through the orifice plate 24.

For this purpose, the housing 12 includes a pair of opposed finger pads28 arranged diametrically opposite each other at the web 22 of thehousing 12. When pressure is applied to the housing 12 via the fingerpads 28, the housing deforms laterally and adopts an elliptical shapecreating a pair of opposed ports on either side of the orifice plate 24through which fluid can flow bypassing the orifice of the orifice plate24 to commence fluid flow in the flow control device 10. Thus, a simplepriming action is provided by the flow control device 10.

In addition, as shown in FIG. 2 of the drawings, due to the constructionof the substantially H-shaped housing 12, no chambers are defined in thehousing 12 thereby minimising the likelihood of air bubble entrapment.Once again, it will be appreciated that air bubble entrapment can be asignificant impediment when considering the size of the orifice 34 ofthe orifice plate 24.

The flow control devices 10 may be made available with housings 12 ofvarious colours. The flow control devices 10 are therefore colour codedwith the colours of the housings 12 being representative of particularflow rates provided by the orifice plate 24 of the relevant flow controldevices 10. Thus, personnel can be trained to select the correct flowcontrol device 10 for a particular application merely by learning thedifferent colours associated with the different flow rates.

The device 10 described with reference to FIGS. 1 and 2 of the drawingsis a single flow rate device. Should it be desired, using the singleflow rate device 10, to change the flow rate of equipment with which theflow control device 10 is used, it is necessary to remove the selectedflow control device 10 from between the conduit 16, 20 and to interposea new flow control device, having a different orifice plate 24 and,hence, flow rate, between the conduits 16, 20.

FIGS. 3 to 9 of the drawings show embodiments of flow control deviceshaving adjustable flow rates.

In FIG. 3 of the drawings, the flow control device is designatedgenerally by the reference numeral 30. The flow control device 30includes a delivery arrangement, or duct, 32 for delivering fluid to beinfused from a container of the fluid. A plurality of spaced orifices 34are defined in a wall 36 of the delivery duct 32. Each orifice 34 isdefined by an orifice plate 24 of the type used in the single flow rateflow control device 10, the orifice 34 being described in greater detailbelow.

A passage defining member 38 is displaceably arranged relative to thedelivery duct 32. In the embodiment illustrated in FIG. 3 of thedrawings, the passage defining member 38 is a rotary actuator 39defining an arcuate passage or channel 40 which cooperates with acorrespondingly arcuate portion 41 of the delivery duct 32.

A supply duct 42 is in fluid flow communication with the passage 40 andsupplies fluid from the flow control device 30 to a patient.

In use, fluid is delivered, as illustrated by arrow 44, via the deliveryduct 32 and through at least one of the orifices 34 into the passage 40.Fluid flows from the passage 40, under gravity, through the supply duct42 as illustrated by the arrow 46.

To adjust or vary the flow rate of fluid in the supply conduit 42, therotary actuator 39 is rotated relative to the delivery duct 32 so thatthe desired number of orifices 34 are brought into fluid flowcommunication with the passage 40. As more orifices 34 come intoregister with the passage 40, the flow rate through the flow controldevice 30 increases and vice versa.

In FIG. 4 of the drawings, another embodiment of an adjustable flow rateflow control device is illustrated. With reference to FIG. 3 of thedrawings, like reference numerals refer to like parts, unless otherwisespecified.

In this embodiment, the supply duct 42 is telescopically received withinthe delivery duct 32. By displacing the supply duct 42 relative to thedelivery duct 32 in the direction of arrows 50, a greater or fewernumber of orifices 34 is brought into communication with the passage 40.In this embodiment, the supply duct 42 itself forms the passage definingmember.

In both embodiments, the conduit 16 attaches to the delivery duct 32 andthe conduit 20 attaches to the supply duct 42, spigot-socket fashion.Instead, the delivery duct 32 and the supply duct 42 may function as theconduits 16, 20 respectively.

Further, in both embodiments, to prime the flow control device 30, atleast the supply duct 42 is of a resiliently flexible material so that apumping action effected laterally on a wall of the supply duct 42effects priming of the device 30. In the case of the embodiment of FIG.3, the rotary actuator 39 may, in addition or instead, be of aresiliently flexible material to effect priming by laterally deforming awall of the actuator defining the passage 40.

Instead, to effect priming, at least one of the orifices 34 is notdefined by an orifice plate 24 but, rather, is constituted by an openingwhich allows priming. Once flow has commenced, this opening is closedoff. The priming may be self-closing, eg. by being spring-loaded.

Referring now to FIGS. 5 to 8 of the drawings, a further embodiment of arotary adjustable flow rate flow control device 30 is illustrated. Withreference to FIGS. 3 and 4 of the drawings, like reference numeralsrefer to like parts, unless otherwise specified.

In this embodiment, the delivery arrangement 32 includes a housing 58defining a first flow path in the form of an arcuate channel 60 in asurface 62 of the housing 58. The channel 60 communicates with an inlet63 of the housing 58. The conduit 16, in use, is attached to the inlet63.

The device 30 includes the rotary actuator 39 separated from the surface62 of the housing 58 by a separating element in the form of a gasket 64.The rotary actuator 39 defines the arcuate passage or channel 40 whichforms a second flow path.

The gasket 64 carries a plurality of spaced orifice plates 24 eachdefining at least one orifice 34. As described above with reference toFIG. 3 of the drawings, as the rotary actuator 39 is rotated, a greateror fewer number of orifices 34 is brought into communication with thechannel 40.

As shown more clearly in FIG. 8 of the drawings, the gasket 64 definesan opening 66 which is in register with an outlet 68 defined in thehousing. The opening 66, in turn, communicates with the arcuate passage40 to enable fluid, which has passed from the first flow path throughthe orifices 34 of the orifice plates 24 into the second flow path toexit the flow control device 30 through the outlet 68 into the supplyduct 42. Once again, the conduit 20 is, in use, connected to the supplyduct 42.

Referring now to FIG. 9 of the drawings, a further embodiment of alinearly adjustable flow rate flow control device is illustrated. Onceagain, with reference to FIGS. 3 to 8 of the drawings, like referencenumerals refer to like parts, unless otherwise specified. In thisembodiment, the delivery arrangement or duct 32 defines an inlet 65. Theinlet 65 is in flow communication with orifice plates 24 carried by thegasket 64 via a the first flow path defined by the duct 32.

The supply duct 42 is arranged on an opposed side of the gasket 64 andhas the passage 40 in flow communication with the orifice plates 24.

By slidably displacing the supply conduit 42 in the direction of arrows50 the desired number of orifices 34 can be brought into communicationwith the passage 40 of the duct 42 to be fed, through an outlet 68,which is an exit aperture of the supply conduit 42, to the conduit 20,connected, in use, to the supply duct 42, for infusion into a patient.

In all the embodiments above with respect to the adjustable flow rateflow control devices 30, the rotary actuator 39 or the supply duct 42,as the case may be, is attached by a ratchet like mechanism. As a resultwhen the rotary actuator 39 or the supply duct 42 is displaced, anaudible click is heard by the user as each orifice 34 is exposed oroccluded, as the case may be, so that the user knows how many orifices34 are open or closed.

In the application of the flow control device 10, 30 in an intravenous(IV) administration set, the flow control device 10, 30 is arrangedbetween the two conduits 16, 20. The conduit 16 leads from a dripcounter (not shown) of a container (also not shown) of fluid to beinfused. The container may either be a flexible or a rigid container.The conduit 20 has a Luer attached to its end opposite the end attachedto the flow control device 10, 30 for enabling parenteral infusion offluids into the patient to be effected.

When such an IV set is used with the flow control device 10, 30 the flowrate is governed by a number of factors. These factors include thepressure head developed as a result of gravitational feed of the fluid.Thus, the container of fluid is, in use, arranged at an elevatedposition relative to the patient. Further, the flow rate is dependent onthe viscosity of the fluid and, thirdly, the degree of back pressureoccurring as the fluid enters the patient.

Insofar as viscosity is concerned, temperature changes can cause a greatvariance in viscosity. With a manual roller clamp of the type presentlyin use, this can result in dramatic differences in the flow rate offluid in the IV set.

The orifice plate 24 used with the single flow rate flow control device10 or defining the orifices 34 of the variable flow rate flow devices30, as the case may be, has a frustoconical orifice 34. Thefrustoconical orifice 34 is formed by laser drilling in the orificeplate 24. In forming the orifice 34 by laser drilling, the size of thehole is measured in real time while being drilled to stop drilling whenan outlet opening 52 is of the required cross sectional area. Generally,the outlet opening 52, being the smaller end of the frustum, is circularbut circularity of the outlet opening 52 is not critical. What is ofgreater relevance is the angle, θ, and the cross sectional area, A, ofthe outlet opening 52 of the orifice 34.

The Applicants have found that, with a constant angle, θ, a linearvariation in flow rate for a varying cross sectional area A is achieved.This is shown in greater detail in FIG. 6 of the drawings where it isshown that the relationship between cross sectional area and flow rateis governed by an equation of the form:—y=mx±c.  Equation 1where:

y=flow rate in ml/hr;

x=cross-sectional area, A, of the orifice 34; and

m and c are constants governed by the angle of the frustum of theorifice 34.

For an angle θ of approximately 24°, the equation is y=0.0107x−2.5804.

The orifice 34 has a length, l, in the range of 60 to 90 μm, moreparticularly, about 70 to 80 μm and, optimally, about 75 μm. The orifice34 has an aspect ratio, being defined as the ratio between the length,l, and the diameter of the opening 52, which is less than or equal to 10and, preferably, about 2.

The orifice plate 24 is of a suitable metal or rigid plastics materialwhich, as indicated above, is laser drilled to form the orifice 34.

Flow rate through the orifice is governed by the following equation:—Flowrate=A√{square root over (P/ρ)}  Equation 2where:

A=cross sectional area of the orifice 34;

P=pressure drop across the orifice 34; and

ρ=density of the fluid.

It will therefore be noted that with the use of the orifice 34 of thetype described above, flow rate is independent of viscosity and isproportional to the square root of the pressure drop across the orifice34. Thus, with the use of such a flow control device 10, 30, a moreaccurate, constant flow rate can be achieved and variations in viscosityof the fluid do not affect the flow rate through the orifice 34 to anysignificant extent.

The conduits 16, 20, as well as the housing 12 of the flow controldevice 10, may be of a polymeric material. Instead, these components maybe of a synthetic elastomeric material, more particularly, a siliconematerial. To inhibit kinking and to improve the elasticity at least ofthe conduits 16, 20, the conduits 16, 20 are reinforced with areinforcing member 54. The reinforcing member 54 is a helical element atleast partially embedded in a wall 56 of the conduits 16, 20. Thereinforcing member 54 is either of a suitable metal material, such asstainless steel, nickel-titanium alloy, or the like or, instead, thereinforcing member 54 is of a suitable plastics material, such as nylon.With the provision of the reinforcing member 54, kinking of the conduit16, 20, is inhibited and, counter-intuitively, such conduits 16, 20,work more efficiently with conventional manual roller clamps as well.

It is an advantage of at least the preferred embodiments of the flowcontrol devices 10, 30 that they do not have chambers in which air canbe trapped preventing the flow of fluid through the IV set with whichthat flow control device 10, 30 is used. In addition, a flow controldevice 10, 30 is provided which is able to maintain a constant flow ratemore accurately than other non-electromechanical devices of which theApplicants are aware. The flow control devices 10, 30 do not require anyspecialist training for use nor do they require continuous monitoring bymedical personnel.

Further, where the conduits 16, 20 are of a silicone material it makesthem easy to join to other silicone components by use of a siliconeadhesive and, for joining to non-elastomeric components, are able toseal with the use of sealing rings, etc.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

The invention claimed is:
 1. An intravenous administration setadjustable flow rate flow control device which includes an intravenousfluid delivery arrangement having an inlet and a plurality of spacedorifice plates, each defining an orifice configured to deliver a meteredquantity of intravenous fluid, all of the orifices being simultaneouslyin fluid flow communication with the inlet via a single conduit, thefluid delivery arrangement including a separating element, comprisinggasket of a resiliently flexible material, with the gasket carrying theorifice plates; and a passage defining member displaceably arrangedrelative to the delivery arrangement downstream of the orifices, thepassage defining member defining a passage which is able to be broughtinto direct fluid flow communication with a desired number of orificesto achieve a desired flow rate through an outlet, which is incommunication with the passage of the passage defining member, byadjusting the position of the passage defining member relative to theorifices of the delivery arrangement, the flow rate through the outletbeing dependent on the number of orifices in direct communication withthe passage of the passage defining member.
 2. The device of claim 1which includes a supply duct in flow communication with the passagedefining member.
 3. The device of claim 1 in which the fluid deliveryarrangement includes a housing defining the single conduit, the singleconduit comprising a first flow path, with the passage of the passagedefining member defining a second flow path.
 4. The device of claim 3 inwhich the separating element separates the first flow path from thesecond flow path.
 5. The device of claim 1 in which the gasket defines aplurality of openings with each opening of the gasket having one of theorifice plates received in it.
 6. The device of claim 5 in which theoutlet is defined in the housing and in which the gasket has an openingdefined through it in alignment with the outlet so that fluid that haspassed through the orifices is able to flow out through the outlet viathe passage of the passage defining member.
 7. The device of claim 5 inwhich the passage defining member includes a rotary actuator which isrotatably arranged relative to the housing, the passage being defined ina body of the rotary actuator.
 8. The device of claim 2 in which thesupply duct constitutes the passage defining member, the supply ductbeing slidably arranged relative to the delivery arrangement to bringthe desired number of orifices into fluid communication with thepassage.